Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Physics A Mathematical and Theoretical

Practical security of continuous-variable quantum key distribution involving saturation attack with finite-size analysis

Yun Mao, Yin Li, Ying Guo

Published May 17, 2022• 4 citations
Publisher

Abstract

Abstract Saturation attack of imperfect detectors compromises the practical security of continuous-variable quantum key distribution (CVQKD) in implementations. In this paper, we demonstrate the practical security of the CVQKD system with finite-size analysis when considering effects of saturation attack on imperfect detectors at the receiver. We suggest an approach to resisting this attack by embedding an adjustable optical filter in the detector, motivated by characteristics of saturation attack. Numerical simulations illustrate the practical security of the system with finite-size analysis in terms of the achieved secret key rate and maximal transmission distance. It indicates that this approach can be elegantly used for defeating the potential saturation attack in practical quantum networks.

DOI
10.1088/1751-8121/ac7093

Related papers

Counteracting a Saturation Attack in Continuous-Variable Quantum Key Distribution Using an Adjustable Optical Filter Embedded in Homodyne Detector

Shengjie Xu, Yin Li, Yun Jie Mao +1 more

A saturation attack can be employed for compromising the practical security of continuous-variable quantum key distribution (CVQKD). In this paper, we suggest a countermeasure approach to resisting this attack by embedding an adjustable optical filter (AOF) in the CVQKD system. Numerical simulations illustrate the effects of the AOF-enabled countermeasure on the performance in terms of the secret key rate and transmission distance. The legal participants can trace back the information that has been eavesdropped by an attacker from the imperfect receiver, which indicates that this approach can be used for defeating a saturation attack in practical quantum communications.

Entropy•Mar 9, 2022•6 citations

Saturation attack on discretely modulated continuous-variable quantum key distribution over an atmospheric turbulence channel

Wenqi Jiang, Hang Zhang, Di Jin +1 more

Continuous-variable quantum key distribution (CVQKD) over an atmosphere channel provides the possibility of global coverage, which is threatened by the imperfection of actual devices. Exploiting imperfections of practical devices, an eavesdropper steals the information between legal participants by performing the potential saturation-induced attacks on the homodyne detector. In this paper, we demonstrate the feasibility of the potential saturation attack in discretely modulated (DM) CVQKD over atmospheric turbulence. Subsequently, a countermeasure is suggested by using an adjustable optical filter (AOF) to attenuate the estimated parameter with the measured value in the finite linearity domain, where the attenuated data can be compensated. Numerical simulations illustrate the effects of the saturation attack on the performance of the AOF-based CVQKD system. We find that legal participants evaluate the information that has been eavesdropped because the secret key rate is made negative.

Journal of the Optical Society of America B•Sep 21, 2022•1 citation

Quantum hacking: Saturation attack on practical continuous-variable quantum key distribution

Hao Qin, Rupesh Kumar, Romain Alléaume

We identify and study a security loophole in continuous-variable quantum key distribution (CVQKD) implementations, related to the imperfect linearity of the homodyne detector. By exploiting this loophole, we propose an active side-channel attack on the Gaussian-modulated coherent-state CVQKD protocol combining an intercept-resend attack with an induced saturation of the homodyne detection on the receiver side (Bob). We show that an attacker can bias the excess noise estimation by displacing the quadratures of the coherent states received by Bob. We propose a saturation model that matches experimental measurements on the homodyne detection and use this model to study the impact of the saturation attack on parameter estimation in CVQKD. We demonstrate that this attack can bias the excess noise estimation beyond the null key threshold for any system parameter, thus leading to a full security break. If we consider an additional criterion imposing that the channel transmission estimation should not be affected by the attack, then the saturation attack can only be launched if the attenuation on the quantum channel is sufficient, corresponding to attenuations larger than approximately 6 dB. We moreover discuss the possible countermeasures against the saturation attack and propose a countermeasure based on Gaussian postselection that can be implemented by classical postprocessing and may allow one to distill the secret key when the raw measurement data are partly saturated.

arXiv:1511.01007•Physical Review A•Jul 15, 2016•150 citations

Saturation attack of the microwave-propagated continuous variable quantum key distribution in open air

Wenqi Peng, Xuan Li, Yongxin Feng +2 more

Abstract Continuous variable quantum key distribution (CVQKD) can achieve the secure communication between two distant legitimate users. The microwave CVQKD exhibits stronger robustness than the optical CVQKD in transmitting quantum signals and accordingly has broad application prospects in quantum networks. Although the microwave CVQKD does not rely on the traditional optical fibers to transmit quantum signals, its practical security is still vulnerable to saturation attacks. In view of this security vulnerability, we generalize saturation attacks to microwave CVQKD and clarify the impact of saturation attacks on the parameter estimation of microwave systems. Two saturation attack schemes are further compared, one based on displacement control alone and the other on joint displacement and gain control. To mitigate the negative impacts caused by this attack, we propose a countermeasure based on the quantum k nearest neighbor algorithm, which can detect saturation attacks by measuring unknown quantum states. In addition, the influence of microwave antennas on the security of the communication system is assessed, confirming that antenna gain plays a key role in determining both the secret key rate and the maximum transmission distance.

New Journal of Physics•Jul 1, 2026•1 citation

Practical Security of Continuous Variable Quantum Key Distribution Ascribable to Imperfect Modulator for Fiber Channel

Shengzhe Xu, Zicheng Zhou, Ying Guo

An amplitude modulator plays an essential role in the implementation of continuous-variable quantum key distribution (CVQKD), whereas it may bring about a potential security loophole in the practical system. The high-frequency modulation of the actual transmitter usually results in the high rate of the system. However, an imperfect amplitude modulator (AM) can give birth to a potential information leakage from the modulation of the transmitter. To reveal a potential security loophole from the high-frequency AM embedded in the transmitter, we demonstrate an influence on the practical security of the system in terms of the secret key rate and maximal transmission distance. The results indicate the risk of this security loophole in the imperfect AM-embedded transmitter. Fortunately, the legal participants can trace back the potential information leakage that has been produced from the imperfect transmitter at high frequencies, which can be used for defeating the leakage attack in CVQKD. We find the limitations of the imperfect AM-embedded transmitter of the high-frequency quantum system, and hence, we have to trade off the practical security and the modulation frequency of the AM-embedded transmitter while considering its implementation in a practical environment.

Mathematics•Apr 29, 2024•1 citation

Practical security of continuous-variable quantum key distribution with reduced optical attenuation

Yi Zheng, Peng Huang, Anqi Huang +2 more

In a practical continuous-variable quantum key distribution (CVQKD) system, the optical attenuator can adjust the Gaussian-modulated coherent states and the local oscillator signal to an optimal value for guaranteeing the security of the system and optimizing the performance of the system. However, the performance of the optical attenuator may deteriorate due to the intentional and unintentional damage of the device. In this paper, we investigate the practical security of a CVQKD system with reduced optical attenuation. We find that the secret key rate of the system may be overestimated based on the investigation of parameter estimation under the effects of reduced optical attenuation. This opens a security loophole for Eve to successfully perform an intercept-resend attack in a practical CVQKD system. To close this loophole, we add an optical fuse at Alice's output port and design a scheme to monitor the level of optical attenuation in real time, which can make the secret key rate of the system evaluated precisely. The analysis shows that these countermeasures can effectively resist this potential attack.

arXiv:1904.08777•Physical Review A•Jul 9, 2019•43 citations
Abstract Saturation attack of imperfect detectors compromises the practical security of continuous-variable quantum key distribution (CVQKD) in implementations. In this paper, we demonstrate the practical security of the CVQKD system with finite-size analysis when considering effects of saturation attack on imperfect detectors at the receiver. We suggest an approach to resisting this attack by embedding an adjustable optical filter in the detector, motivated by characteristics of saturation attack. Numerical simulations illustrate the practical security of the system with finite-size analysis in terms of the achieved secret key rate and maximal transmission distance. It indicates that this approach can be elegantly used for defeating the potential saturation attack in practical quantum networks.
A saturation attack can be employed for compromising the practical security of continuous-variable quantum key distribution (CVQKD). In this paper, we suggest a countermeasure approach to resisting this attack by embedding an adjustable optical filter (AOF) in the CVQKD system. Numerical simulations illustrate the effects of the AOF-enabled countermeasure on the performance in terms of the secret key rate and transmission distance. The legal participants can trace back the information that has been eavesdropped by an attacker from the imperfect receiver, which indicates that this approach can be used for defeating a saturation attack in practical quantum communications.
Continuous-variable quantum key distribution (CVQKD) over an atmosphere channel provides the possibility of global coverage, which is threatened by the imperfection of actual devices. Exploiting imperfections of practical devices, an eavesdropper steals the information between legal participants by performing the potential saturation-induced attacks on the homodyne detector. In this paper, we demonstrate the feasibility of the potential saturation attack in discretely modulated (DM) CVQKD over atmospheric turbulence. Subsequently, a countermeasure is suggested by using an adjustable optical filter (AOF) to attenuate the estimated parameter with the measured value in the finite linearity domain, where the attenuated data can be compensated. Numerical simulations illustrate the effects of the saturation attack on the performance of the AOF-based CVQKD system. We find that legal participants evaluate the information that has been eavesdropped because the secret key rate is made negative.
We identify and study a security loophole in continuous-variable quantum key distribution (CVQKD) implementations, related to the imperfect linearity of the homodyne detector. By exploiting this loophole, we propose an active side-channel attack on the Gaussian-modulated coherent-state CVQKD protocol combining an intercept-resend attack with an induced saturation of the homodyne detection on the receiver side (Bob). We show that an attacker can bias the excess noise estimation by displacing the quadratures of the coherent states received by Bob. We propose a saturation model that matches experimental measurements on the homodyne detection and use this model to study the impact of the saturation attack on parameter estimation in CVQKD. We demonstrate that this attack can bias the excess noise estimation beyond the null key threshold for any system parameter, thus leading to a full security break. If we consider an additional criterion imposing that the channel transmission estimation should not be affected by the attack, then the saturation attack can only be launched if the attenuation on the quantum channel is sufficient, corresponding to attenuations larger than approximately 6 dB. We moreover discuss the possible countermeasures against the saturation attack and propose a countermeasure based on Gaussian postselection that can be implemented by classical postprocessing and may allow one to distill the secret key when the raw measurement data are partly saturated.
Abstract Continuous variable quantum key distribution (CVQKD) can achieve the secure communication between two distant legitimate users. The microwave CVQKD exhibits stronger robustness than the optical CVQKD in transmitting quantum signals and accordingly has broad application prospects in quantum networks. Although the microwave CVQKD does not rely on the traditional optical fibers to transmit quantum signals, its practical security is still vulnerable to saturation attacks. In view of this security vulnerability, we generalize saturation attacks to microwave CVQKD and clarify the impact of saturation attacks on the parameter estimation of microwave systems. Two saturation attack schemes are further compared, one based on displacement control alone and the other on joint displacement and gain control. To mitigate the negative impacts caused by this attack, we propose a countermeasure based on the quantum k nearest neighbor algorithm, which can detect saturation attacks by measuring unknown quantum states. In addition, the influence of microwave antennas on the security of the communication system is assessed, confirming that antenna gain plays a key role in determining both the secret key rate and the maximum transmission distance.
An amplitude modulator plays an essential role in the implementation of continuous-variable quantum key distribution (CVQKD), whereas it may bring about a potential security loophole in the practical system. The high-frequency modulation of the actual transmitter usually results in the high rate of the system. However, an imperfect amplitude modulator (AM) can give birth to a potential information leakage from the modulation of the transmitter. To reveal a potential security loophole from the high-frequency AM embedded in the transmitter, we demonstrate an influence on the practical security of the system in terms of the secret key rate and maximal transmission distance. The results indicate the risk of this security loophole in the imperfect AM-embedded transmitter. Fortunately, the legal participants can trace back the potential information leakage that has been produced from the imperfect transmitter at high frequencies, which can be used for defeating the leakage attack in CVQKD. We find the limitations of the imperfect AM-embedded transmitter of the high-frequency quantum system, and hence, we have to trade off the practical security and the modulation frequency of the AM-embedded transmitter while considering its implementation in a practical environment.
In a practical continuous-variable quantum key distribution (CVQKD) system, the optical attenuator can adjust the Gaussian-modulated coherent states and the local oscillator signal to an optimal value for guaranteeing the security of the system and optimizing the performance of the system. However, the performance of the optical attenuator may deteriorate due to the intentional and unintentional damage of the device. In this paper, we investigate the practical security of a CVQKD system with reduced optical attenuation. We find that the secret key rate of the system may be overestimated based on the investigation of parameter estimation under the effects of reduced optical attenuation. This opens a security loophole for Eve to successfully perform an intercept-resend attack in a practical CVQKD system. To close this loophole, we add an optical fuse at Alice's output port and design a scheme to monitor the level of optical attenuation in real time, which can make the secret key rate of the system evaluated precisely. The analysis shows that these countermeasures can effectively resist this potential attack.